text: from django.apps import apps
  from django.contrib.sites.models import Site
  from django.core.cache import cache
  from django.test import TestCase, modify_settings, override_settings
  
  from .models import I18nTestModel, TestModel
  
  
  @modify_settings(INSTALLED_APPS={'append': 'django.contrib.sitemaps'})
  @override_settings(ROOT_URLCONF='sitemaps_tests.urls.http')
  class SitemapTestsBase(TestCase):
      protocol = 'http'
      sites_installed = apps.is_installed('django.contrib.sites')
      domain = 'example.com' if sites_installed else 'testserver'
  
      def setUp(self):
          self.base_url = '%s://%s' % (self.protocol, self.domain)
          cache.clear()
          # Create an object for sitemap content.
          TestModel.objects.create(name='Test Object')
          self.i18n_model = I18nTestModel.objects.create(name='Test Object')
  
      @classmethod
      def setUpClass(cls):
          super().setUpClass()
          # This cleanup is necessary because contrib.sites cache
          # makes tests interfere with each other, see #11505
          Site.objects.clear_cache()
  